Sewing machine



United States Patent Michael Grundfest [72] Inventor 99-41 64th Ave., Forest Hills, New York 11274 [21] Appl. No. 778,595

[22] Filed Nov. 25,1968

[45] Patented Sept. 8, 1970 [54] SEWING MACHINE 5 Claims, 7 Drawing Figs.

[52] US. Cl 112/214 [51] Int. Cl D05f27/10 [50] Field of Search... 112/203, 204, 214

[56] References Cited UNITED STATES PATENTS 2,229,647 1/194] Gardner et al ll2/2 14 2,325,643 8/1943 Weis 112/214 Primary Examiner-Mervin Stein Assistant Examiner-George V. Larkin Alt0rney--J0hn P. Chandler ABSTRACT: A sewing machine having a flat bed providing a work support and having sewing elements operating above and below the work, a top structure supporting the sewing elements above the work piece and which can be raised clear of all contact with a fixed lower structure, the structures having pairs of cooperating upper and lower rollers with the work piece positioned therebetween, the lower rollers driving the upper rollers by frictional contact while feeding the work piece, the upper rollers having a driving connection with the upper sewing elements, a motor driven shaft in the lower structure with a driving connection with the lower rollers and with the sewing elements below the base, and electromagnetic means for registering the movable structure with the fixed lower structure.

Patented Sept. 8, 1970 U 3,527,182

\ Sheet 1 of 3 llllllffl INVENTOR.

MICHAEL GRUN DFEST JOHN P. CHANDLER HIS ATTORNEY.

Patented Sept. 8, 1970 INVENTOR.

MICHAEL GRUNDFEST JOHN P. CHANDLER HIS ATTORNEY.

Patented Sept. 8, 1970 3,527,182

Sheet '5 of 3 INVENTOR.

MICHAEL GRUNDFEST JOHN P. CHANDLER HIS ATTORNEY.

SEWING MACHINE This invention relates to sewing machines and has for its principal object the provision of an improved machine wherein the entire surface of the flat bed providing the worksupporting base is unobstructed from side to side and frorr front to back so that there is no limtation as to the width of the work which can be operated upon. In prior machines, this limitation results from the persistent presance of an upright tubular standard extending upwardly from the work supporting base, the standard having an upper overhanging horizontal arm of limited length terminating in a hollow upright head. The mechanism, including a vertically reciprocating needle bar, which functions above the work piece, is actuated by means extending through this hollow standard and horizontal arm which is synchronized with the means operating below the work piece.

The improved machine can use the identical mechanisms above the work piece, or any improved mechanisms, but they are driven by a plurality of pairs of upper and lower friction rollers which transmit torque from the lower drive rollers to the upper driven rollers by surface contact with the cloth or other work piece positioned between the roller, which latter also feed the cloth.

The entire mechanism above the work piece can be suspended from above, 1'. e. the ceiling, and can be lifted clear of any contact with the flat bed and its associated equipment. This superstructure, or upper part, including the needle bar, is held in perfect registry with the moving and fixed parts in the substructure or lower part by cooperating electromagnetic elements.

The driving rollers on each side of the fiat bed are normally driven at the same speed so that work is fed in a straight line to produce a straight stitch line. The right and left hand drives are variable, however, to produce a curved stitch.

It will be appreciated that the new arrangement affords greater flexibility of operation and greater freedom for the operation.

In the drawings:

FIG. 1 is a front elevation of the machine of the present invention;

FIG. 2 is a plan view of flat bed forming the work support,

along line 2-2 of FIG. 1', FIG. 3 is a plan view of the lower wall of the upper housing,

along line 3-3 ofFIG. l; 1

FIG. 4 is a vertical longitudinal section taken through the machine;

FIG. 5 is a section along line 5-5 of FIG. 4;

FIG. 6 is a section along line 6-6 of FIG. 5; and

FIG. 7 is a section along line 7-7 of FIG. 4.

The machine of the present invention has a flat bed 10 providing a work-supporting base and forming the upper wall ofa housing 11 having end walls 12 and 14, a front wall 17 and a base wall 16 suitably supported in spaced relation to the floor. A bed plate 18 having a needle opening 19 covers conventional lower sewing mechanism which forms no part of the present invention and accordingly is not illustrated. The needle is indicated at 20 mounted at the lower end ofa needle bar 21 and all other details of the upper sewing mechanism are omitted, such mechanism being contained in an enclosure 22 positioned in an upper housing 24.

A main drive shaft 26 is journalled for rotation in bearing plates 28 and 29 and is connected with a motor shaft 30 by a coupling 31. The motor 32 is secured to end wall 14 outside of housing 11. A gear 34, keyed to shaft 30, drives an idler 36 keyed to shaft 37 and also keyed to an aligned extension 37' of this shaft is a gear (FIG. 6) which drives gears 39 and 40 in the same direction. These gears mesh with gears 41 and 42 keyed to shafts 44 and 46 suitably journalled in bearing plates 48 and 49. Keyed to these shafts are the fiist set of friction drive and feed wheels 50 and 51. Shaft 37 passes through a variable speed mechanism 53 adjusted by knob 54 on a shaft 56 extending through front wall 17. Shaft 37 is an extension of shaft 37 aligned therewith.

Main drive shaft 26 extends to the other end of housing 11 where the gearing mechanism of the right hand end is duplicated. As seen in FIG. 4, this includes gear 56, fast on shaft 26, gear 57 on shaft 59, which enters speed variation unit 60, gear 61 on shaft 62, gear 64 on shaft 66 which carries friction drive wheel 68.

The upper perpheries of friction drive wheels 50 and 68 project slightly above flat bed 10 through rectangular holes 70 and engage the lower face of the work piece 71.

Upper housing 24 can be suitably supported by means (not shown) extending from the ceiling above and so arranged as to retain the upper friction drive wheels 72 and 73 in driving relation to the lower friction wheels with the flexible work piece therebetween. These wheels are keyed to two sets of aligned stub shafts 74 and 75 journalled in frame members 76 and 77, shaft 74 having a gear 69 fast therein. Gear 69 on shaft 74 drives a gear 79 on a shaft 78 which extends into the enclosure 22 for the upper sewing mechanism to drive the upper sewing mechanism such as the needle bar. This enclosure is supported by lateral frame members 80 and 81.

The electromagnetic registering mechanism is an important feature of the present invention. In the lower housing 11, this includes front and rear laminated U-shaped cores 84 provided with windings 85 whose upper terminals 86 and 88, respectively, extend through holes 89 in the flat bed 10 and generate a magnetic field that extends above the flat bed. There are two elongated pole pieces 91 extending across openings 92 in the lower wall 94 of the upper floating structure. These are permanent magnets of soft magnetic material and are located within the lines of magnetic force of the magnetic field generated by the electromagnets 86 and 88. The soft magnetic material has a high magnetic permeability and, as a result, will concentrate the magnetic field of the electromagnet so as to produce a high mechanical force of attraction and hold the pole pieces and the top mechanism precisely registered. When the lower magnets are deenergized, the top can be freely lifted and moved since the holding force of the permanent magnets of the polepiece assembly is of very low order.

It is not necessary to provide suspension means from the ceiling to support the upper part, including rollers 72 and 73. It is preferred, however, to have some means for raising the upper part from friction wheels 50 and 51.

I claim:

1. In a sewing machine having a flat bed providing a work supporting base for a work piece and having sewing elements operating above and below the work piece, including thread feeding and stitch forming means, the improvement which includes a top structure supporting those sewing elements above the work piece and which can be raised clear of all contact with a fixed lower structure, the structures having pairs of cooperating upper and lower rollers with the work piece positioned therebetween, the lower rollers driving the upper rol- Iers by frictional contact while feeding the work piece, means effecting a driving connection between at least one of the upper rollers and the sewing elements supported in the top structure, a motor driven shaft in the lower structure with a driving connection with the lower rollers and with the sewing elements below the base, and means for creating an electromagnetic field between the structures for registering the movable structure relative to the fixed lower structure.

2. The machine of claim 1 wherein the registering means is an electromagnet in the fixed structure, the terminals of whose core extend to the top of the flatbed, and a permanent magnet in the top structure which is located in the lines of magnetic force.

3. The machine of claim 1 wherein there are provided two sets of front and rear lower rollers engaged by an equal number of upper rollers.

4. The machine of claim 1 wherein the means for driving the lower rollers includes a motor connected with the motor driven shaft, idler gears driven by the motor driven shaft, a pair of gears driven by gears connected with each idler and a pair of gears driven by said latter gears and which together 5. The machine of claim 4 wherein speed adjusting means are positioned between each idler and the gear it drives. 

